Synthesis and characterisation of neutral mononuclear cuprous complexes based on dipyrrin derivatives and phosphine mixed-ligands
作者:Xiaohui Liu、Hongmei Nan、Wei Sun、Qikai Zhang、Mingjian Zhan、Luyi Zou、Zhiyuan Xie、Xiao Li、Canzhong Lu、Yanxiang Cheng
DOI:10.1039/c2dt30618b
日期:——
Heteroleptic neutral mononuclear cuprous complexes with dipyrrin derivatives and phosphine mixed-ligands including 1,3,7,9-tetramethyldipyrrin (1), 5-phenyl-1,3,7,9-tetramethyldipyrrin (2), 2,8-dibromo-1,3,7,9-tetramethyldipyrrin (3), 1,9-dichloro-5-phenyldipyrrin (4), 1,9-dibromo-5-phenyldipyrrin (5), 5-pentafluorophenyl-1,3,7,9-tetramethyldipyrrin (6) and 1,5,9-triphenyldipyrrin (7) have been synthesized and fully characterized. The central Cu(I) atoms of these complexes in general formulas of Cu(1–6)(PPh3)2 (1a–6a) and Cu(1–6)(DPEphos) (1b–6b) [DPEphos = bis(2-diphenylphosphinophenyl)ether] all exhibit a pseudo-tetrahedral geometry, while complex Cu(7)(PPh3) (7a) is tricoordinated in a pyramidal conformation due to the large steric hindrance of ligand 7. The oxidation potentials assigned to oxidations of Cu(I)–Cu(II) are extraordinarily low in the range of 0.36–1.02 V vs. Ag/AgCl compared with traditional [Cu(phen)(PP)]+ analogues. Their emission maxima range from 495 to 595 nm in dichloromethane at room temperature with quantum yields of 0.05–4.03% and lifetimes on the order of nanoseconds. Unlike the characteristic MLCT emission in cationic Cu(I) complexes, the emissions are assigned to the dipyrrin-centered intraligand charge transition (ILCT) based on the fact that the increased conjugation within the dipyrrinato anion leads to a weaker metal–ligand interaction, thus preventing the mixing of π orbitals of ligand and 3d orbitals of Cu(I) atom. This conclusion is also supported by electrochemical data and theoretical calculations.
合成了一系列含有二吡咯甲川衍生物和膦混合配体的杂配位中性单核亚铜配合物,并用 1,3,7,9-四甲基二吡咯甲川(1)、5-苯基-1,3,7,9-四甲基二吡咯甲川(2)、2,8-二溴-1,3,7,9-四甲基二吡咯甲川(3)、1,9-二氯-5-苯基二吡咯甲川(4)、1,9-二溴-5-苯基二吡咯甲川(5)、5-(五氟苯基)-1,3,7,9-四甲基二吡咯甲川(6)和1,5,9-三苯基二吡咯甲川(7)进行了全面表征。这些配合物的中心Cu(I)原子通常具有伪四面体几何构型,通式为Cu(1~6)(PPh3)2(1a~6a)和Cu(1~6)(DPEphos)(1b~6b)[DPEphos=二(2-二苯基膦苯基)醚],而配体7由于空间位阻较大,使得配合物Cu(7)(PPh3)(7a)表现出三角锥形的结构。与传统的[Cu(phen)(PP)]+类似物相比,这些配合物中Cu(I)到Cu(II)的氧化电位在0.36至1.02 V(vs. Ag/AgCl)的范围内异常低。它们在室温下的二氯甲烷中的最大发射波长范围为495至595 nm,量子产率为0.05至4.03%,寿命为纳秒级。与阳离子Cu(I)配合物中的特征MLCT发射不同,这些配合物的发射被归因于二吡咯甲川中心的配体内电荷跃迁(ILCT),这是因为二吡咯甲川阴离子内部共轭程度的增加导致金属与配体之间的相互作用减弱,从而阻止了配体π轨道与Cu(I)原子的3d轨道的混合。这一结论也得到了电化学数据和理论计算的支持。